Tire Sizing Woes

I recently purchased a pair of 700×40 Ritchey SpeedMax Cross tires.  I wanted more volume and tread than my normal tires, and I figured the SpeedMax would fit the bill.  Well, it turns out I was wrong.  When mounted on 23mm rims, the Ritcheys measured only 34.25mm wide.  I’m accustomed to tires measuring a little narrower than claimed, but this really confused me, as Ritchey also offers this tire in 32mm and 35mm versions.

Because it’s marketed as a cross tire, maybe Ritchey is worried that someone might show up at a UCI-sanctioned event, only to be DQ’d because of their too-wide tires.  If it was a 32 or 35, then maybe the width discrepancy would make more sense, but we’re talking about a tire that’s marked 40-622.  Someone choosing a tire this wide probably wants a tire that’s larger than a 35 (or 37).

Now, to be perfectly fair, this is not the first time I’ve run into this issue.  My 700×37 Conti Contacts measured 33-34mm (on the rim), and my 700×42 Contact Extra Lights are only 37mm wide (on 23mm wide rims).  Interestingly enough, Vittoria’s Randonneur Hypers measure true to size, and in some instances, are actually wider than claimed.

Don’t get me started on frame sizing and measurements…